Pulsacoil 2000 Peak rate boost problem

I am not getting any hot water from the on peak boost from my pulsacoil 2000.

The off peak works ok but if I use up all the hot water I don't get anymore hot water if I try using the on peak boost supply.

The green light is on, the red light on the board is flashing 2 per second meaning no errors i believe.

Please can you advise on what the problem might be?

I have had alot of parts replaced on this boiler over the last 2 years and seem to get a fault every 6 months or so. Is this normal, are they generally really unreliable, or am I just unlucky?

Thanks
Craig

just check that the cut out safey button has not popped out

Where is the reset button?

Can anybody tell me where the safety button is please, is it on the stat or board? I can't see it.

Thanks